Mesenchymal stem cells (MSCs) are an adult stem cell population, typically isolated from bone marrow aspirates, and are capable of self-renewal, expansion in culture, and differentiation into adipocytes, chondrocytes, and osteoblasts. These cells are being explored for use in tissue engineering applications, such as spinal fusions, bone defect repairs, and cartilage regeneration. In general, to attain cell numbers required for these applications, the cells are typically expanded in culture over a number of passages;however, the ex vivo expansion of these cells has been shown to induce changes in gene expression and affect the ability of these cells to differentiate. This suggests that the use of MSCs as a therapeutic would be most efficacious with high numbers of freshly isolated cells, but would require impractical amounts of bone marrow to be feasible. Adipose derived stem-cells (ASCs) have been proposed as an alternative to bone marrow-derived MSCs in several clinical indications. These cells are estimated to be 500-fold more abundant per gram of adipose tissue compared to the number of MSCs in a similar mass of bone marrow. Furthermore, adipose tissue is more abundant and more easily obtained with less patient morbidity than bone marrow. Therefore, we hypothesize that the development of an ASC enrichment system would allow for point-of-care isolation of large numbers of autologous cells, thereby eliminating the need for ex vivo expansion prior to implantation. In this proposal, we will employ our core platform technology-phage display biopanning-to identify an ASC-binding peptide and test its ability to isolate these adult stem cells from adipose tissue. In parallel research programs, we have identified peptides capable of isolating MSCs from bone marrow aspirate preparations with minimal cross-reactivity with other cell types, thereby validating the approach of this proposal. We will first identify ASC-binding peptides using phage display, then couple the peptides to a resin. This peptide-coated matrix will be used for the optimization of ASC binding and elution conditions using cultured cells and to enrich ASCs from the crude cellular fraction of lipoaspirates. Finally, we will characterize the ASC surface markers and their ability to differentiate into three lineages to ensure that exposure to our peptide did not affect the stem-like qualities of these cells. Based on our results with MSC isolation, we envision that a product consisting of a solid support matrix coupled to our ASC-binding peptide would allow for the isolation of autologous ASCs-a cell population that is more easily accessible and abundant than that of bone marrow-for point-of-care therapeutic use. PUBLIC HEALTH RELEVANCE: Adult stem cells are beginning to appear in new medical products. Typically, these cells are mesenchymal stem cells derived from bone marrow. However, their low numbers in bone marrow require the cells to be isolated and expanded ex vivo prior to their incorporation into a marketed product. Here, we seek to develop a novel stem cell-binding reagent to harvest stem cells from adipose tissue. Adipose-derived stem cells are far more numerous than those derived from bone marrow. This increase could potentially enable point-of-care use of adipose-derived stem cells, allowing a surgeon to harvest and deploy cells from autologous sources in a surgical procedure. We currently envision this peptide-based reagent to be used in a culture-free method of ASC isolation prior to their use in tissue engineering applications.